tomcraft Posted June 27, 2011 Share Posted June 27, 2011 I have a 71 240z with 383 sbc.I just recently replaced an open 3.54 diff. With a 3.7 gleason torsen LSD .To my surprise on hard takeoff my tires spin way easier than they used to.I also installed 15/8 shorty headers replacing ram horn style .I was wondering what you guys think? is it higher gearing or the headers.I was always very surprised at how well it used to hold the ground and I was hoping for even better results and now I have to keep the rpm below 3500 or I just start spinning .I have a muncie m20 4 speed.Thanks for thoughts and or suggestions. Quote Link to comment Share on other sites More sharing options...
wheelman Posted June 27, 2011 Share Posted June 27, 2011 (edited) It's mostly due to the additional torque the 3.7:1 ratio transmits to the wheels. The shorty headers may have gained you a few HP but not so much that it would be noticeably easier to spin the tires. You might be better off mating that Torsen to the 3.54:1 gears, you'd be back at the ratio you were happier with and have the LSD. Edited June 27, 2011 by wheelman Quote Link to comment Share on other sites More sharing options...
tomcraft Posted June 27, 2011 Author Share Posted June 27, 2011 Thanks,that's what I assumed but not ever changing out gears before I didn't realize how much of a difference it would make.I thought the extra grip would handle the extra torque.there is a slight wine in the new diff so that might not be a bad idea.Wish I knew if my 1/4 mi. times are better but never been to the track.Is the slight whine normal with a gleason unit? Quote Link to comment Share on other sites More sharing options...
Mike C Posted June 30, 2011 Share Posted June 30, 2011 Increased torque from the 3.73 although not a lot. Were the rams horns 2" exit or 2 1/2"? If they were 2, you could see quite a bit more power from 2500 rpm up with the shorty headers. Quote Link to comment Share on other sites More sharing options...
Tony D Posted June 30, 2011 Share Posted June 30, 2011 The whine is from the ring and pinion, not the ATB unit...it will go 'CLUNK!' when transferring torque when it starts to get sloppy... Quote Link to comment Share on other sites More sharing options...
tomcraft Posted June 30, 2011 Author Share Posted June 30, 2011 (edited) Thanks, that's good to know.no clunk.Is there a rule of thumb as far as choosing the right gearing between rear and tranny for best 1/4 mile times.Should tires start to spin at certain rpm or is the goal to minimize spin at all cost?to no one suprise I'm a noob but would like to set car up to be as good as it can because I'm hoping to get it to the track when time and $ allows me.Thanks.Yes they were 2" Edited June 30, 2011 by tomcraft Quote Link to comment Share on other sites More sharing options...
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